Almost every tank containing liquids needs a vent of some sort to allow gasses to escape as liquids are added to the tank, or air to re-enter to replace liquids being drawn out of the tank; as well as to allow the escape of volatile gasses or fumes. On a boat, and particularly in regard to gasoline tanks, where the vapors are explosive, these vents must be outside of the hull. This poses special problems, since any vent to the outside of the hull must be exposed to the elements of the weather, and especially to rain and spray, which, if either were to enter the vent, could be quite damaging to the fuel--and ultimately the engine--or could contaminate whatever is in the tank. It is also important to provide screening to keep out insects and other foreign matter.
This invention is an improvement over my earlier device covered in U.S. Pat. No. 4,706,840, dated Nov. 17, 1987, for a "Baffled Tank Vent". This and other typical tank vents, with or without valves, will perform similar functions but with similar problems. A one-way valve could prevent most contaminants from getting in, but it could also block the flow of air into the tank, which would inhibit one of the functions of the vent, and could be critical.
The vent should not be unattractive, and it must not project too far from the outside of the hull to become vulnerable to breakage or other physical damage. It must be strong enough to stand occasional physical abuse, and should be easily removable for cleaning, repair, or replacement. It must also have a screening effect to keep bugs, that would not be good for the fuel or the engine, out of the tank.
It is therefore an object of this invention to provide a vent that extends through the side of a hull in a simple and secure manner, but also includes an unique combination of baffles to provide protection against rain, spray, and insects.